Despite assurances from developer Namco that the Xbox Live Arcade version of Soul Calibur would feature "no major additions or subtractions" over the beloved Dreamcast edition, the recent port lacks the original's substantial Mission Mode.

Essentially the game's single-player campaign, Mission Mode provided players with hours of additional gameplay through various objective-based fights, and also served as a means to unlock new content. All of the unlockable items, such as characters and concept art, are now immediately available at the game's outset.
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Mission Mode's absence eliminates the bulk of the single-player gameplay from the fighter, which was released yesterday as a $10 download on the Xbox 360.

All of the title's other modes--Arcade, Time Attack, Team Battle, Practice, Survival, Extra Survival, Museum and the offline-only Vs Battle--remain intact.

Namco has yet to comment on the reason behind the exclusion. It is likely that the 188 MB title entered development while the previous150 MB XBLA file size limit was in effect, though prioritizing bonus artwork over an entire gameplay mode seems curious.